1. Field of the Invention
This patent relates to fire resistant non-metallic industrial containers. More particularly, this patent relates to industrial containers such as fibre drums, plastic drums and composite intermediate bulk containers having an outer layer of fire resistant intumescent material incorporated into the container structure.
2. Description of the Related Art
Industrial containers made from non-metallic materials of construction (e.g., fibre drums, plastic drums, and composite intermediate bulk containers) may undergo rapid failure under test fire conditions, spilling ladings which, if flammable or combustible, can feed a fire and possibly lead to the more serious loss of the storage facility. For example, in a standard pool fire, a water-filled 55 gallon fibre or plastic drum will fail (spill its contents) in about 3-4 minutes, and a composite IBC (e.g., a 275 gallon capacity polyethylene bottle inside a steel rod cage) will fail in about 90 seconds. If an adequate water sprinkler system is provided, these containers can last indefinitely in such a fire without discharging their contents. The challenge is to provide an industrial container that will survive until the sprinkler system is activated.
Extension of container survival time can provide a sufficient margin of safety such that the containers would be approved under existing fire codes for storage of flammable and/or combustible liquids in protected warehouses (i.e., warehouses whose fire suppression systems and stacking patterns meet the requirements of Section 4.8 of NFPA-30, the Flammable and Combustible Liquids Fire Code).
It has been found that adding an outer layer of intumescent material to non-metallic containers is useful in preventing the rapid failure of such containers in a warehouse fire. The intumescent material swells or expands when heated to form a layer of non-combustible material, sometimes called char, between the combustible non-metallic container surface and the air.
The active ingredient in many intumescent paints is polyammonium phosphate, which emits a gas at elevated temperatures but at lower-than charring temperatures. When the paint is first exposed to elevated temperatures, the gas swells the paint. Upon further heating, the foamed paint chars, forming a low density but coherent ash which insulates the substrate from further heat.
It is known in the art that intumescent coatings may be used as fireproofing agents to protect combustible surfaces. However, not until now has it been suggested that an intumescent layer be added to the outside of an extruded plastic container or a fibre drum for the purpose of providing a container that could be approved under existing fire codes for storage of flammable and/or combustible liquids in protected warehouses.
Thus it is an object of the present invention to provide a non-metallic container that will survive in a fire for a sufficient period of time to allow a sprinkler system to be activated and/or to allow time for fire-fighting personnel to arrive and begin to fight the fire.
A further object of the present invention is to provide a fire protected non-metallic container in which the fire protective feature is incorporated into the structure of the container.
A still further object of the present invention is to provide a fire protected plastic or fibre drum in which a fire protective intumescent layer forms part of the container structure.
Further and additional objects will appear from the description, accompanying drawing, and appended claims.